The automotive industry is more and more oriented in the integration of active exhaust components, towards the reduction of fuel consumption, reduced emission of pollutants, reduced noise levels. A key feature towards these highly sensitive requirements is the design of the exhaust valve for specific combustion engine and vehicle applications.
In particular, active valves become more and more applied in exhaust systems, particularly for use in exhaust systems for combustion engines with cylinder deactivation technology, the cylinder deactivation generally occurring during partial load operation of the engine. Under partial load, these engines will switch off one or more cylinders leading to significant deterioration of the noise. Active acoustical valves, generally active acoustic butterfly valves, are used to this purpose. The acoustic valves can be switched from fully closed over any intermediate position to fully open position by an actuator to optimize the noise reduction depending on the vehicle operating conditions. Hence, active acoustical valves allow for an optimal noise level in all operating conditions of the engine with internal combustion.
Besides the development efforts for the design of an appropriate valve, each valve may be combined with different actuators depending on the requirements of the automotive industry, particularly regarding the supplier for the actuator. For the same valve, several different actuator suppliers may be selected—A same valve may therefore be paired with different actuators, leading to laborious development efforts for adapting the valve to each actuator. Additionally, each valve/actuator pairing has to be validated before serial production. For large production quantities, such development and validation efforts may be negligible. There are, however, specific areas in which the production quantities are small and the costs for development and validation of various valve/actuator combinations considerable compared to the production quantities.
Specifically, the use of valve units in exhaust systems for combustion engines with cylinder deactivation technology or for high power engines is particularly challenging because of the relatively small production quantities, leading to time consuming development and validation efforts resulting in high costs compared to the small sales volume for such valve units.
It is therefore an object of the invention to suggest a valve unit which overcomes the above mentioned drawbacks and offer an improved valve unit.